"fastest" flash, and using a pencil to overclock.

[Jubadub]

That's still on-topic and relevant! Thanks for sharing that code, it's neat! Never heard of DFS before, but from what I see it basically underclocks (halves it, in this case) the processor without requiring hardware modifications. Is this kind of configuration stored in PRAM, meaning it's reset/undone when we replug the mini and hold the power button at the same time?

So a 1.82 GHz processor would lower to 0.91 Ghz or something... Well, that's still kinda neat and cool to know. Although I'd rather keep the stock 1.5 GHz setting in that case.

Edit: Just leaving some useful links below.
http://oldcomputer.info/apple/macmini/index.htm
https://web.archive.org/web/20180119025115/http://www.lbodnar.dsl.pipex.com/macmini/
https://web.archive.org/web/20070206043057/http://macminiforums.com/forums/showthread.php?t=178
https://web.archive.org/web/2016051...odnar.dsl.pipex.com/macmini/macmini_board.jpg

 

[DearthnVader]

What we did for the Mini under OS 9 to reduce heat and fan noise was to enable NAP mode.

Doesn't really help much when the CPU is under full load, only better cooling can do that.

 

[Jubadub]

On the topic of running the Mac mini G4 cooler, I saw this on MacOS9Lives just a moment ago:

https://eshop.macsales.com/item/NewerTech/NUCUBE/

One thing they claim is that it enables "the mini to run cooler than the normal horizontal position" and they "heat-tested" it to draw that conclusion.

Now as a skeptic, I can't believe that at face value, but let's assume this store actually has a point, and that the minis run cooler in a vertical position. Would anyone be able to explain how that is true, on a physics/chemistry level? In both cases, the hot air goes up, and is then pushed outside with the fans. Fundamentally, does anything change?

 

[jmilan0302]

Sorry for bumping this back from the dead, but I'm onto this, and it seemed to make more sense to bring back this thread than to make a new one.

I have a bunch of stock 1.5 GHz Mac mini G4s, and I'm willing to try to get one of them to reach 1.82 GHz, the maximum clock found in Reflex88's table, the thread starter. But I also want to make it stable. Viable, perhaps. There may be a fault in the following reasoning, but I figure the most likely reason 1.82 GHz is less stable is because of heat.

As such, I'd love suggestions & overall pro-tips on how we could bring CPU temperature down on this Mac mini model as much as possible. Reapplying the thermal paste & making sure to use high quality silver thermal paste (i.e. Arctic Silver, but not one of the fakes such as Arcticline Silver etc.) is the bare minimum that ought to be done in our overclocking scenario, but I'd also love ideas to take it a bit further, if anyone has them!

All I could think of is only the most simple:
- Change heatsink (is there one that is bigger and/or of a more heat-transfering material than the one that comes stock? Reflex88 mentioned he also had heard that later 1.2 GHz minis came with a worse heatsink than earlier ones...);
- Change fan (bigger and/or stronger fans could be used? What voltage ought they not surpass?).

I guess more hardcore & non-ideal solutions would be to keep the upper lid removed for maximum air ventilation, and also install a liquid-cooling system (lol), but such extreme measures would take away all the point of the Mac mini G4, in my opinion! Not that I think anyone wanting to do so should be stopped, though. In fact, it'd be kind of cool to see...
As for changing fan & heatsink, does anyone know what are the biggest dimensions we can consider?

Ultimately, my mission is too see how much we can push such a compact, convenient Mac OS 9 box like the mini! (Also a convenient OS X, GNU/Linux, BSD & MorphOS box!)

But if we just can't address the thermal issue for 1.82 GHz, then of course the fallback plan would be to settle with 1.75 GHz.

Maybe replace the heatsink with something better? You can find 40x40/50x50mm (whatever fits, measure the stock heatsink) copper heatsinks for pretty cheap on Aliexpress, maybe replace the stock one with one of those? Next step in OCing a mini would be replacing the CPU with a 7448.

 

[Reflex88]

BUMP!

Just out of interest, Did any one get 1.8 out of a mini, stable?

I'd image running without the optical drive probably helps lower the mini's internal temperatures.. and an SSD? Perhaps run with the HDD outside the case, running a sata (is it sata, been a few years now since I had one open) out through the optical drives slot?

 

[Reflex88]

Hello! Slight bump, sort of on topic.

I've just removed the "active" led from a laptop web cam so it can be a CCTV cam without letting the naughty folk know EXACTLY where it's hidden...

Anyway, I took the led off the board and the cam stopped working! I was about to abandon the PCB but then remembered this pencil trick, drew my graphite resistor where the LED had been and what'a'ya know.. the camera works again!! And now it's subtle!

... So, did anyone get 1.82ghz? Optical drive out, extra case fan powered from the now redundant drive power? Extra holes drilled through the top?

 

[jmilan0302]

Hello! Slight bump, sort of on topic.

I've just removed the "active" led from a laptop web cam so it can be a CCTV cam without letting the naughty folk know EXACTLY where it's hidden...

Anyway, I took the led off the board and the cam stopped working! I was about to abandon the PCB but then remembered this pencil trick, drew my graphite resistor where the LED had been and what'a'ya know.. the camera works again!! And now it's subtle!

... So, did anyone get 1.82ghz? Optical drive out, extra case fan powered from the now redundant drive power? Extra holes drilled through the top?

1.8 will probably need more voltage.

 

[ervus]

I got one of these minis to run at 2GHz, but any prolonged CPU activity would lock it up. So I made a copper heat sink for it. This helped, but eventually it would still overheat. I could up the voltage, but that would also exacerbate the heat issue. So I backed it down to 1.92GHz and it seems happy there.

What would be nice is to install a 7448 chip in these computers. Unfortunately the firmware will not allow it. Does anyone know how to fix the firmware?

 

[Strategia]

I created a spreadsheet containing values from 1 to 2GHz, and I think it is accurate. So far I have gotten my 1.42 to 1.58, but once my recently ordered Arctic MX-4 arrives I'll try to push it more. It seems to have given the Mini the extra oomph it needs to run Leopard well since Core Image is done through the CPU.

 

[Strategia]

Though most people will probably want to stay in the 1 to 2GHz range (6x to 12x), here are all the possible values. If you wanted to create a 333MHz Mac mini or even a theoretical 3.5 GHz mini (with liquid nitrogen?), here you go. To calculate the frequency, take the front side bus (167 MHz or 1/6) and multiply it by the multiplier you want. 0 means the resistor is activated, and 1 means it isn't.
1st digit - R52
2nd digit - R362
3rd - R355
4th - R351
5th - R358

 

[Amethyst1]

If you wanted to create a 333MHz Mac mini or even a theoretical 3.5 GHz mini (with liquid nitrogen?), here you go.

Now what kind of voltage (and cooling) would a 3.5 GHz G4 need?

 

[Jubadub]

What would be nice is to install a 7448 chip in these computers. Unfortunately the firmware will not allow it. Does anyone know how to fix the firmware?

Yes, by running an updater, such as Giga Designs'. Dosdude1 installed a 7448 clocked at 2.0GHz on an iMac G4 less than a year ago:

Friendly reminder to anyone unaware, the 7448 is also a drop-in upgrade for the 7447, such as the one in all Mac mini G4s, as per the CPU manufacturer's documentation:

https://www.nxp.com/docs/en/fact-sheet/MPC7448FACT.pdf

Every G4 in the world should be 7448-upgraded. Someone should start selling modified MDD CPU modules reballed with them (and 7457s, for those few apps that really exploit L3 cache). Although I hear the stock MDD CPU modules would need an extra, small adapter board for 7447/7448 (not needed for 7457), and that could perhaps imply a different heatsink has to be used than the stock one. No such adapter should be needed if you install 7448s on Sonnet's MDX CPU board designed for MDDs and Xserve G4s, though.

NXP (who bought Freescale, who branched off Motorola) still sells fresh new 7448 processors on their website, and they are actively produced, even in the year 2021. The 7457 processors are still sold there, as well (unlike the 7447), but are no longer manufactured. You can find those (and older processors) on eBay, too, often much cheaper, in case you plan to get rich by selling people 7448-upgraded Mac minis and MDD CPU modules. *wink wink*

 

[ervus]

The limitation is the apple firmware. It does not allow upgraded CPUs. The aftermarket upgrade companies all had ways to patch the firmware, but these patches only work on a few models. If we could patch other models, then we could upgrade them too.

Does anyone know how to fix the firmware?

 

[Jubadub]

The limitation is the apple firmware. It does not allow upgraded CPUs. The aftermarket upgrade companies all had ways to patch the firmware, but these patches only work on a few models. If we could patch other models, then we could upgrade them too.

Does anyone know how to fix the firmware?

I'd be shocked if the Giga Designs firmware patch works with the iMac G4, as seen in the video, but not with the Mac mini G4. Did you try getting a 7448 soldered into a Mac mini G4 after using the Giga Designs updater + correct NVRAM flags yet? And it failed? Asking just to see if I'm following you correctly. Perhaps you have a complete and thorough list that tell us all G4 Macs with which those updaters necessarily work with, and with which they don't, and that's what allows you to conclude the available firmware patches would work with iMac G4s, but not the minis?

 

[Strategia]

Did you try getting a 7448 soldered into a Mac mini G4 after using the Giga Designs updater + correct NVRAM flags yet? And it failed?

In the 2.0GHz iMac G4 thread Dosdude1 said he was unable to get the 7448 to work on the Mac mini; even with the Giga Designs patch. I'd be interested to see someone else try however.

Well, I have just confirmed that BootROM version 4.7 is indeed patchable by the Giga Designs patch. So, that means ANY 1/1.25 GHz iMac G4 can be upgraded to a 7447 CPU. I have also attempted manually patching the firmware on a G4 Mac Mini and upgrading that to a 7448, but unfortunately it doesn't work... There must be some hardware incompatibility with the 7448 on these systems.

 

[dosdude1]

In the 2.0GHz iMac G4 thread Dosdude1 said he was unable to get the 7448 to work on the Mac mini; even with the Giga Designs patch. I'd be interested to see someone else try however.

It turns out this is because the firmware implementation is not quite the same on the G4 Mini as it is on other systems. I'll just have to learn some PPC assembly and figure out how to patch it manually.

 

[dosdude1]

Also, I have somewhat recently managed to come across a large amount of 7448s and 7457s, so I'll be able to perform quite a lot of upgrades and experimentation.

 

[Jubadub]

Ten 7448 @1.7GHz and ten 7457 @1.267Ghz. Oh boy. *drool*

And, thanks for the clarification on the mini, guys, I stand corrected. Crazy idea, but what if the mini firmware was flashed over with another Mac model's firmware? At worst I guess not even Open Firmware would be accessible (likely to be the case?), but at best could there be partial or even full compatibility? And then the Giga Designs patch could be applied?

Worst case scenario, the minis can still be upgraded today as is with a 7447 @1.667GHz base clock speed, usually overclockable to 2.0Ghz while remaining stable (if Sonnet 1.8GHz 7447 upgrades are any indicator).

Regardless, it would be good to know whether or not the only G4 model affected by this problem is the mini. May every G4 be overtaken by 7448 @2.0Ghz+ upgrades!

 

[DearthnVader]

Also, I have somewhat recently managed to come across a large amount of 7448s and 7457s, so I'll be able to perform quite a lot of upgrades and experimentation.

View attachment 1727927View attachment 1727928View attachment 1727929

Did you ever dump the firmware before, and after, applying on of the patches so we can look at it in a hex editor and see if we can figure out exactly what these firmware updates are changing?

 

[DearthnVader]

Crazy idea, but what if the mini firmware was flashed over with another Mac model's firmware? At worst I guess not even Open Firmware would be accessible (likely to be the case?), but at best could there be partial or even full compatibility?

What's that I smell, capacitors burning and resistors popping?

 

[Jubadub]

What's that I smell, capacitors burning and resistors popping?

Yes, that's probably a more realistic (and probable) worst case scenario. lol

 

[DearthnVader]

Yes, that's probably a more realistic (and probable) worst case scenario. lol

Very high probability, but I like the way you think 🤣

I'm the dark lord of ill-advised mods, and have the dead logic boards and CPU cards to prove it.

 

[LightBulbFun]

Did you ever dump the firmware before, and after, applying on of the patches so we can look at it in a hex editor and see if we can figure out exactly what these firmware updates are changing?

me and @dosdude1 did actually, and he tried manually applying said patches to the Mac Mini's BootROM after comparing before and after dumps of the iMac's ROM but it still did not work sadly

Crazy idea, but what if the mini firmware was flashed over with another Mac model's firmware? At worst I guess not even Open Firmware would be accessible (likely to be the case?), but at best could there be partial or even full compatibility? And then the Giga Designs patch could be applied?

you joke but thats exactly what we did when me and Dosdude where figuring out the iMac G4 upgrades, we used the BootROM from a PowerBook5,6 IIRC, and it actually did work, well it chimed (but obviously did not get much further because of the different GPUs)

but that told us it was OpenFirmware on the iMac holding us up rather then a hardware incompatibility

we figured it would be worth doing since both machines have very similar hardware wise otherwise, both use the Intrepid north bridge etc

but with regards to the 7448, theres no 7448 compatible mac we can cross flash a Mac Mini too (although im not sure if we tried flashing a patched iMac BootROM to one but the iMac and Mac Mini do use different sound and PMU setups which might throw a spanner in the works)



I also just for fun flashed Mac Mini firmware to a Macbook which also worked LOL

going off the Firmware deep end.

I have no idea where this thread would actually fit on the Mac Rumors forum so im just going to stick it in here since I know yall appreciate a vintage mac :) so I have a MacBook2,1 (Late 2006 Core 2 Duo T7200) which had a broken screen so I removed the LCD assembly to make a Mac "Pancake" as...

forums.macrumors.com

you can also Flash MacPro5,1 firmware to an Xserve3,1 for what its worth

obviously cross flashing firmware like this is very risky and even if it does work you may be left with some hardware not working (like some of the RAM slots in an Xserve3,1 do not work after flashing with MP5,1 FW)

 

[Akulareb]

Also, I have somewhat recently managed to come across a large amount of 7448s and 7457s, so I'll be able to perform quite a lot of upgrades and experimentation.

That's great news, I still wonder of a 17" with 7448

 

[dosdude1]

I just spent a couple hours learning a little bit of PPC assembly, and managed to re-create the GigaDesigns ROM patch in a Mac Mini G4 BootROM! This patch does EXACTLY what the GD patch does to compatible ROMs, so I see no reason at all why this wouldn't work to get a 7448 booting on a Mac Mini G4 (I don't have mine with me, but will test once I do). My custom patched ROM is attached, although it does contain my serial number and other identifiers, so it should be used for testing only at this time (I will make a script that will in-place patch a dumped ROM in the future). Also attached are a few assembly control flow diagrams, displaying the function in question, of various ROMs, so you can see what was done.